Memsorb™, a novel CO removal device part II: in vivo performance with the Zeus IE.

Memsorb™ (DMF Medical, Halifax, Canada) is a novel device based upon membrane oxygenator technology designed to eliminate CO from exhaled gas when using a circle anesthesia circuit. Exhaled gases pass through semipermeable hollow fibers and sweep gas flowing through these fibers creates a diffusion gradient for CO removal. In vivo Memsorb™ performance was tested during target-controlled closed-circuit anesthesia (TCCCA) with desflurane in O/air using a Zeus IE® anesthesia workstation (Dräger, Lübeck, Germany).

Memsorb™, a novel CO removal device part I: in vitro performance with the Zeus IE®.

Soda lime-based CO absorbents are safe, but not ideal for reasons of ecology, economy, and dust formation. The Memsorb™ is a novel CO removal device that uses cardiopulmonary bypass oxygenator technology instead: a sweep gas passes through semipermeable hollow fibers, adding or removing gas from the circle breathing system. We studied the in vitro performance of a prototype Memsorb™ used with a Zeus IE® anesthesia machine when administering sevoflurane and desflurane in O/air mixtures.

In vitro efficiency of 16 different Ca(OH) based CO absorbent brands.

Data directly comparing CO absorbents tested in identical and clinically relevant conditions are scarce or non-existent. We therefore tested and compared the efficiency of 16 different brands of Ca(OH) based CO absorbents used as loose fill or a cartridge in a refillable canister under identical low flow conditions. CO absorbents efficiency was tested by flowing 160 mL/min CO into the tip of a 2 L balloon that was ventilated with an ADU anesthesia machine (GE, Madison, WI, USA) with a tidal volume of 500 mL and a respiratory rate of 10/min while running an O/air FGF of 300 mL/min.

In vitro performance of prefilled CO absorbers with the Zeus®.

Low fresh gas flows (FGFs) decrease the use of anesthetic gases, but increase CO absorbent usage. CO absorbent usage remains poorly quantified. The goal of this study is to determine canister life of 8 commercially available CO absorbent prepacks with the Zeus.

Low Pressure Robot-assisted Radical Prostatectomy With the AirSeal System at OLV Hospital: Results From a Prospective Study.

Background: Limited studies examined effects of pneumoperiotneum during robot-assisted radical prostatectomy (RARP) and with AirSeal. The aim of this study was to assess the effect on hemodynamics of a lower pressure pneumoperitoneum (8 mmHg) with AirSeal, during RARP in steep Trendelenburg 45° (ST).

Materials And Methods: This is an institutional review board-approved, prospective, interventional, single-center study including patients treated with RARP at OLV Hospital by one extremely experienced surgeon (July 2015-February 2016).

Desflurane usage during anesthesia with and without NO using FLOW-i Automatic Gas Control with three different wash-in speeds.

AGC (Automatic Gas Control) is the FLOW-i's automated low flow tool (Maquet, Solna, Sweden) that target controls the inspired O (FO) and end-expired desflurane concentration (Fdes) while (by design) exponentially decreasing fresh gas flow (FGF) during wash-in to a maintenance default FGF of 300 mL min. It also offers a choice of wash-in speeds for the inhaled agents. We examined AGC performance and hypothesized that the use of lower wash-in speeds and NO both reduce desflurane usage (Vdes).

Inhaled anaesthetics and nitrous oxide: Complexities overlooked: things may not be what they seem.

This review re-examines existing pharmacokinetic and pharmacodynamic concepts of inhaled anaesthetics. After showing where uptake is hidden in the classic FA/FI curve, it is argued that target-controlled delivery of inhaled agents warrants a different interpretation of the factors affecting this curve (cardiac output, ventilation and blood/gas partition coefficient). Blood/gas partition coefficients of modern agents may be less important clinically than generally assumed.

Accuracy of inhaled agent usage displays of automated target control anesthesia machines.

Automated low flow anesthesia machines report how much inhaled anesthetic agent has been used for each anesthetic. We compared these reported values with the amount of agent that had disappeared by weighing the vaporizer/injectors before and after each anesthetic. The vaporizers/injectors of the Aisys, Zeus and FLOW-i were weighed with a high precision weighing scale before and after anesthesia with either desflurane in O2/air or sevoflurane in O2/N2O.

Automated gas control with the Maquet FLOW-i.

The FLOW-i anesthesia machine (Maquet, Solna, Sweden) can be equipped with automated gas control (AGC), an automated low flow tool with target control of the inspired oxygen concentration (FIO2) and end-expired concentration (FA) of a potent inhaled anesthetic. We examined the performance and quantitative aspects of the AGC. After IRB approval and individual informed consent, anesthesia in 24 ASA I-II patients undergoing abdominal or gynecological surgery was maintained with sevoflurane in O2/air with a target FIO2 of 40 % and a target sevoflurane FA (FAsevo) of 2.

In vitro performance of prefilled CO₂ absorbers with the Aisys®.

Low flow anesthesia increases the use of CO2 absorbents, but independent data that compare canister life of the newest CO2 absorbents are scarce. Seven different pre-packed CO2 canisters were tested in vitro: Amsorb Plus, Spherasorb, LoFloSorb, Medisorb, Medisorb EF, LithoLyme, and SpiraLith. CO2 (160 mL min(-1)) flowed into the tip of a 2 L breathing bag that was ventilated with a tidal volume of 500 mL, a respiratory rate of 10/min, and an I:E ratio of 1:1 using the controlled mechanical ventilation mode of the Aisys (®) (GE, Madison, WI, USA).

Performance of an active inspired hypoxic guard.

Current hypoxic guards systems fail to maintain the inspired O2 concentration (FIO2) ≥ 21 % across the entire fresh gas flow (FGF) range when a second carrier gas is used (N2O or air). We examined the performance of the Maquet O2 Guard(®), a smart hypoxic guard that increases O2 delivery if an inspired hypoxic mixture is formed. After obtaining IRB approval and informed consent, 12 ASA I-II patients were enrolled.

Development and performance of a two-step desflurane-O(2)/N(2)O fresh gas flow sequence.

Study Objective: To determine if the previously described single-step O(2)/N(2)O fresh gas flow (FGF) sequence could be combined with a simple desflurane vaporizer (F(D)) sequence to maintain the end-expired desflurane (F(A)des) at 4.5% with the anesthesia delivery unit machine (ADU Anesthesia Machine(R); General Electric, Helsinki, Finland).

Design: Prospective randomized clinical study.

Desflurane Consumption During Automated Closed-circuit Delivery is Higher Than When a Conventional Anesthesia Machine is Used With a Simple Vaporizer-O₂-N₂O Fresh Gas Flow Sequence.

Background: The Zeus® (Dräger, Lübeck, Germany), an automated closed-circuit anesthesia machine, uses high fresh gas flows (FGF) to wash-in the circuit and the lungs, and intermittently flushes the system to remove unwanted N₂. We hypothesized this could increase desflurane consumption to such an extent that agent consumption might become higher than with a conventional anesthesia machine (Anesthesia Delivery Unit [ADU®], GE, Helsinki, Finland) used with a previously derived desflurane-O₂-N₂O administration schedule that allows early FGF reduction.

Methods: Thirty-four ASA PS I or II patients undergoing plastic, urologic, or gynecologic surgery received desflurane in O₂/N₂O.

Can Modern Infrared Analyzers Replace Gas Chromatography to Measure Anesthetic Vapor Concentrations?

Background: Gas chromatography (GC) has often been considered the most accurate method to measure the concentration of inhaled anesthetic vapors. However, infrared (IR) gas analysis has become the clinically preferred monitoring technique because it provides continuous data, is less expensive and more practical, and is readily available. We examined the accuracy of a modern IR analyzer (M-CAiOV compact gas IR analyzer (General Electric, Helsinki, Finland) by comparing its performance with GC.

The ideal oxygen/nitrous oxide fresh gas flow sequence with the Anesthesia Delivery Unit machine.

Study Objective: To determine whether early reduction of oxygen and nitrous oxide fresh gas flow from 6 L/min to 0.7 L/min could be accomplished while maintaining end-expired nitrous oxide concentration > or =50% with an Anesthesia Delivery Unit anesthesia machine.

Study Design: Prospective, randomized clinical study.